The present invention relates to a helical scan type video signal recording and reproducing apparatus, and more particularly to a technique for automatically stopping a magnetic tape at an optimum tape position to assure reproduction of a high quality image when fast forward movement of the magnetic tape is stopped to reproduce a still image.
In a home video signal recording and reproducing apparatus (hereinafter referred to as a video tape recorder), a two-head helical scan system is used to effectively utilize the magnetic tape and the gaps of the two video heds are angled to each other so that no guard band is produced between record tracks. In the home video tape recorder, it is common to provide a so-called still image reproduction function in which the movement of the magnetic tape is stopped and the same record track is repeatedly reproduced.
In such a video tape recorder, when an image is reproduced while the magnetic tape is stationary, the tracing locus of the video head has an angle to the tape which is essentially different from that of the record track. Since the gaps of the two heads are angled to each other, it is difficult to read the recorded signal over the entire length of the record track, and a portion of the reproduced image is lost or the vertical synchronizing signal is not reproduced, resulting in a disturbance of the synchronization of the reproduced image.
In order to resolve the above problem, it has been proposed to make the width of the video head wider than the width of the record track, that is, to make the track pitch narrower than the width of the video head. With this scheme, even if the trace locus of the video head does not coincide with the direction of the record track, at least a portion of the head passes over the record track and no part of the reproduced signal is lost.
However, a demand for the effective use of the magnetic tape has been increasing, and recording at higher density has been required in recent years. For example, it has been proposed to enable six-hour recording/reproduction in a video tape recorder which uses a two-hour magnetic tape, by reducing the tape movement velocity to one third of a standard tape movement velocity. In such a circumstance, the width of the video head may be 30 microns, for example, and the track pitch in a long time mode is 20 microns. When the track width is narrow, a hig quality signal is not reproduced in the still image reproduction mode unless precision in machining the magnetic tape guide or mechanical parts, such as the cylinder of the head, is very high. Recording and reproduction at the standard velocity are also required. In the above example, the track pitch at the standard velocity is 60 microns. As a result, a 30 microns record track and a 30 microns non-recorded track, that is, a guard band are produced. As a result, in the still image reproduction mode, when the video head traces across the guard band, no signal is reproduced. As a result, useful image cannot be reproduced under such conditions.